AND DESCRIPTIONS OF NEW SPECIES. 79 



Unio Pustulatus. Plate VII. fig. 9. 



Testa suborbiculari, cBquilaterali, inflatd, margine posteriori emarginata; valvuUs 

 crassis, et duabus tuberculorum seriebus instructis ; dentibus cai'dinalibtcs magnis; 

 later alibus brevibus subrectisque ; margarita alba et iridescente. 



Shell nearly circular, equilateral, inflated, posteriorly emarginate ; valves thick 

 and furnished with two rows of tubercles; cardinal teeth large ; lateral teeth short 

 and nearly straight; nacre pearly white and iridescent. 



^^^ C Ohio, T. G. Lea. 



C Tennessee, Professor Vanuxem. 

 My Cabinet. 

 Cabinet of Professor Vanuxem. 

 Cabinet of P. H. Niekliu. 

 Cabinet of the Academy of Natural Sciences of Philadelphia. 

 Diam. 1-3, Length 1-9, Breadth 2-1 inches. 



Shell nearly circular, equilateral, inflated, posteriorly emarginate, 

 furnished with two vertical rows of tubercles on each valve, one in a 

 direct line from the beaks to the basal margin, the other along the um- 

 bonial slope ; those of the latter resemble pustules. The first tubercle 

 appears on the third growth ; the fourth and each successive growth have 

 two parallel to each other. Posterior margin granulate ; substance of the 

 shell thick ; beaks elevated, slightly recurved, and granulate at the tip ; 

 ligament short and thick ; epidermis yellowish brown and rather smooth; 

 cardinal tooth large, elevated and widely cleft in the left valve, single and 

 emerging from a pit in the right valve ; lateral teeth short and nearly 

 straight ; anterior cicatrices distinct ; posterior cicatrices confluent ; dor- 

 sal cicatrices situated on the under part of the cardinal tooth ; cavity 

 of the beaks deep and angulated ; nacre pearly white and iridescent. 



Remarks. — This species somewhat resembles the U. verrucosus 

 (Barnes), Var. &, erected into a new species in this paper under the 

 name of pustulosus. It differs in being more transverse and in being 

 destitute of the broad single ray which passes from the beak of the 

 latter. In the arrangement of the tubercles it is altogether different ; 



